This is a brief video of how to create powerpoint slides that conceal text/objects but then reveal them via a 'letterbox' behind which you use a motion path to move the concealed object across the gap. If you right click on the link below, you can open the file in a new browser window. You can also right click and download it if you wish.
Download spotlight_feature_and_motion_paths_ppt.swf (14442.0K)
If you want the powerpoint slide from the video, here it is